FIGURE 1.

Ctt1-GFP is a good reporter of the oxidative stress response. A, schematic representation of chromosomal ctt1 tagged with GFP. B, ctt1-GFP strain is not sensitive to oxidative stress. Serial dilutions from cultures of strains 972 (WT), AV18 (Δsty1), EP198 (Δctt1), and PG102 (ctt1-GFP) were spotted onto rich plates without (YES) or with H₂O₂. C, relative levels of ctt1 mRNA by Northern blot. Total RNA from strains 972 (WT) and EP102 (ctt1-GFP), either untreated (0) or treated with 1 mm H₂O₂ for the indicated times, was analyzed by Northern blot with probes for ctt1. rRNA and act1 are shown as loading controls. D, rich media cultures of strains 972 (WT) and PG102 (ctt1-GFP), either untreated (0) or treated with 1 mm H₂O₂ for the indicated times, were analyzed to determine Ctt1-GFP protein levels by Western blot using polyclonal antibody against GFP. Sty1 is shown as a loading control. E, rich media cultures of strains 972 (WT), PG102 (ctt1-GFP), and ES10 (ctt1-GFP Δsty1), either untreated (0) or treated with 1 mm H₂O₂ for the indicated times, were analyzed to determine Ctt1-GFP fluorescence levels by flow cytometry. Results are expressed as FITC/FCS ratio, normalized to the levels of untreated wild-type ctt1-GFP cells, with an assigned value of 1. S.D. were calculated from biological duplicates.